The problem that you are experiencing is most likely because you have Presswork 1.0.3. You need the latest version (1.0.4.1).

Wordpress takes a certain time to validate themes and plugins. Therefore, it is not available at the moment. To download the latest version, go to the Presswork's Github (link below), decompress and replace the current Presswork directory with the new one.

*Please note that if you have applied certain modifications to the Presswork core files, you will need to backup and copy these modifications in order to have them in the latest version.